1 Department of Neurology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
2 Division of Neurology, Department of Medicine, National University Health System and Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
3 Department of Neurology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea. staelee@snu.ac.kr.